The present invention relates to a method for applying a cover layer to a net structure to be used for medical purposes, in particular a thrombosis filter. The invention also relates to a thrombosis filter provided with a cover layer according to this method.
Net structures of this kind can have different applications in medicinal treatments. They can, for example, be used as vessel supports, in particular as stents. In addition to their use as permanent implants, the net structures according to the invention can be used as thrombosis filters, for example during vessel widening (angioplasty) via a cardiac catheter. Finally, the risk of a thrombus forming cannot be excluded in the case of interventions in the blood vessels despite the use of state-of-the-art medical engineering. The known thrombosis filters are placed in folded-together condition in the desired place in the vein, in particular in the flow direction of the blood circulation behind the constriction (stenosis). When opened up it lies on the internal vessel wall before the performance of a balloon angioplasty.
In the case of a balloon angioplasty of this kind, a balloon catheter is inserted from the groin via a guide wire into the stenosis and inflated. The expanded cross section achieved thereby is generally maintained by an implanted stent. It is precisely with an intervention of this kind that there is a risk of thrombotic material dropping off the vessel walls and being transported via the blood stream into narrower vessels. Here, the material can cause a thrombosis or even an embolism, wherein a pulmonary embolism or a stroke can represent a life-threatening emergency. The net structure of the thrombosis filter can then enable any resulting thrombus to be filtered out and removed together with the thrombosis filter. Thrombosis filters of this kind are known, for example, from European Patents EP 1 207 810 B1 and EP 619 720 B1.